The comprehensive Cancer Care Data Management System is being developed and evaluated in the department of Medical Oncology at University Hospital, Boston. The objective of the project is to overcome the deficiencies of traditional medical records and improve patient care for the cancer patient while facilitating clinical research studies. The system operates on a PDP 11 computer under the MUMPS Standard operating system. Detailed but essential medical information will be computer-accessible; paper medical records will be largely computer generated. Information will be collected by way of structured entry forms, supplemented by dictation. Experiments in direct data entry by clinical staff will be performed. The computer will structure the information collection by cueing clinical staff to provide data based on the nature of the cancer, its status, the presence or absence of comorbid disease, prior history and status of the patient, and the nature of any research protocol in use. The system will support patient care decisions prescribed by research protocol or generally agreed upon patient care practice. It will also monitor patient care data, uncovering potential problems and bringing them to the oncologist's attention. The design will maximize transferability to other cancer centers and minimize cost and inconvenience. Sophisticated evaluation techniques will be used to measure the impact on quality of cancer care and clinical research, as well as cost-effectiveness.